Spark plug testers



Oct. 27, 1959 D. w. sHAw 2,910,644

SPARK PLUG TEsTERs Filed July 8, 1955 INVENTOR ATTORNEYS United States Patent SPARK PLUG TESTERS David W. Shaw, Parma, Mo.

Application `luly 8, 1958,V Serial No. 7 47,148

7 Claims. (Cl. 32m-.19.)

This invention relates to certain new and useful provements in spark plug testers,` and more particularly one that can be readily used in connection with spark plugs that have rubber or moisture resistant covers that fit over the terminals of the plugs.

lt is common practice to use Screwdrivers and the like for testing spark plugs such as are employed in connection with internal combustion engines b ut such devices are very inefficient in their use and often result in severe shock to the user.

One of the objects ot this invention is to provide a simple, efficient tester that can be used when the terminals of the spark plugs are covered with rubber caps.

Another object of the invention is to provide a spark plug tester which can be positionedagainst the rubber cap covering the terminal and grounded with the engine, with means for establishing contact with the terminal through the cap at the option of the operatorand which can be quickly removed and applied to adjacent spark plugs without the necessity of disturbing or removing any parts of the plugs or engine.

.A further object is to provide a spark plug tester with a swivel head so that when it is placed in position against the spark plug terminal, the tester may be rotated to such a position that an arm which is pivotally connected to the tester in order to form a ground with the engine block, can form such a contact without the necessity of removing the spark plug tester from contact with the spark plug terminal.

Still another object of the invention is to provide a spark plug tester which, when in position against the spark plug terminal provides a ground for the '00.01A but requires positive action by the operator before a` circuit can be established through the tool.

The invention will be better understood from Vthe detailed description hereinafter following when read in connection with the accompanying drawings in which:

Figure l is a side elevation of the spark plug tester in operative position in relation to the spark plug and the engine block. Certain parts are broken away to better illustrate the construction.

Fig. 2 is an enlarged horizontal sectional view taken along lines 2 2 of Figure l.

Fig. 3 is a fragmentary sectional View taken |along lines 3-3 of Fig, 2; and

Fig. 4 is a vertical sectional view taken along lines 4--4 of Fig. 3.

Referring to the drawings, in which like numerals designate similar parts, numeral 5 designates a spark plug of the usual type mounted in a motor block 6. At the upper end` of the spark plug is the usual terminal 7 with a rubber cap 8 extending over the terminal 7 and an ignition wire 9 which is connected to theterminal 7. A spark plug tester 10 having a cylindrical tube 11 and a semi-circular end plate 12 swivelly mounted at 13 on the end of the tube 11 is adapted to contact the rubber cap 8 at a point opposite the terminal 7. The semif circular plate 12 is held in rotatable position by a stud r* t* LCC member 14 whose head secures the plate 12 in rotatable position on the end of the tube 11 with the opposite end extending into the open end of the tube 11. This end forms a stop member 15 for a spring 16` which sur-` rounds a needle-like member 17 which, in turn, is se. cured to a plunger rod 18. A shoulder formed by the inner face of the plunger rod 18 acts as a stop member for the other end 20. of the spring 16. The plunger rod 18 has a flat recess 21 with a wall 22 at the fore. ward end of the recess 21 forming a shoulder adapted to align with an opening 23 in the tube 11. A stop member 24 carried by a clip 25` which encircles the tube 11, extends into the opening 23 and contacts the wall 22. so as to limit the rearward movement of the plunger rod 18. The clip 25 has extensions, or ears, 26` between which arm 27 is pivotally mounted on a screw 28 which not only serves to support the arm 27, but securely holds t-he stop` member 24 in place in the opening 2 3. The plunger rod 18 is secured to an insulated handle 29` which may be made of plastic or light material.

As actually used, the semi-.circular plate 12 is placed against the rubber cap Si, opposite the terminal 7. The arm 27 which is pivotally mounted on 'the screw 28, drops down into contact with the motor jacket or frame. The needle-like member 1 7 is in retracted position in the tube 11 since the compression spring 16 is bearing against the shoulder, thus exerting pressure against the plunger rod 18.

The operator now desiring to test the spark plug 5, moves the plunger rod 1S forward, thus compressing the spring 16 and, at the same time, forcing the needle.- like member 17 out through the opening 23. The needlelike member 1,7 piercesl the rubber cap 8 and `comes into contact with the terminal 7. This, of course, occurs while `the motor is running. The spark plug tester will work just `as well if no rubber cap is present since the semi-circular plate 12 at the `end of the tube 11 holds the tool'in position around the terminal 7 so that the needlelike member 17 is guided into contact with the terminal 7. Upon the inward pressure on the plunger rod 1.8, being removed, the needle-like member 17 returns io its initial position within the cylindrical tube 11, thus breaking the circuit. The plunger rod 18 in which the needle-like member 17 is mounted, is limited in its rearward movement by the wall 22 coming into contact with the stop member 214 which is carried by the clip 25 eld extends down into the tube 11 through the openmg,

The testing of the spark plug can be repeated aS- many times as desired without removing the testing tool from its position against the spark plug terminal. The passage of the current through the tool can be broken ai the will of the operator and the testing resumed with: out any change of position of the tool in .relation to. the spark plug terminal and engine block. The tool can be quickly removed from anyone spark plug to another without the removal of any part of the spark plug or change in arrangement of the tool. The curved plate 12 being swivelled, permits the tool to assume the proper position in relation to the engine block, and the arm 27 being pivoted will, at all times, be in position.

Having described my invention for purposes of illustration but without intent to be limited thereto, what l claim is as follows:

l. A spark plug tester including, a tube having an aperture in the upper side thereof, a plunger having a recess formed in its upper surface and a wall at one end` of said recess, said plunger slidably mounted in said needle-like member carried by said plunger, resilient means for normally retaining said plunger and needle?v like member within the tube, one end of said needlelike member extensible beyond the end of the tube upon the handle being operated to compress the resilient means, a clip having a stop member and extensions, the stop member extending into the aperture formed in the tube and adapted to contact the wall formed at one end of the recess in the surface of the plunger and limit the movement of the plunger, an arm extending from said clip, and means for connecting the extensions together and providing pivotal means for the arm.

2. A spark plug tester including a tube having an aperture in the upper side thereof, a plunger having a recess formed in its upper surface and a Wall'at one end of said recess, said plunger slidably mounted in said tube, an insulated handle connected to said plunger, a needle-like member carried by said plunger, a compression spring surrounding said needle-like member, a stop member adjacent the open end of the tube for restricting the movement of said spring, the face of the plunger forming a shoulder against which the other end of the spring rests, said compression spring normally retaining said plunger and needle-like member within the tube, one end of said needle-like member extensible beyond the end of the tube upon the handle being operated to compress the spring, a clip having a stop member and extensions, the stop member extending into the aperture formed in the tube and adapted to contact the wall formed at one end of the recess in the surface of the plunger and limit the movement of the plunger, an arm extending from said clip and means for connecting the extensions together and providing pivotal means for the arm.

3. A spark plug tester including a tube having an aperture in the upper side thereof, a plate rotatably mounted on the end of said tube and having an opening therein, said opening being in alignment with said tube, means for rotatably securing said plate to the end of the tube, said means extending into the tube and forming a stop member, a plunger having a recess formed inv its upper surface and a wall at one end of said recess, said plunger slidably mounted in said tube, an insulated handle connected to said plunger, a needle-like member carried by said plunger, a compression spring surrounding said needle-like member, one end of the compression spring resting against the stop member adjacent the open end of the tube for 'restricting vthe movement of said spring, the face of the plunger forming a shoulder against which the other end of the spring rests, said compression spring normally retaining said plunger and needlelike member within the tube, one end of said needle-like member extensible beyond the end of the tube upon the handle being operated to compress the spring, a clip having a stop member and extensions, the stop member extending into the aperture formed in the tube and adapted to contact the wall formed at one end of the recess in the surface of the plunger and limit the movement of the plunger, an arm extending from said clip and means for connecting the extensions together and' providing pivotal means for the arm, said tester rotatable in relation to said plate so that the arm is capable of assuming a vertical position without rotation of the plate and the arm is adjustable to contact portions of the motor block to form a ground.

4. A spark plug tester including, a tube, a plate rotatably mounted on the end of said tube and having an opening therein, a plunger slidably mounted in said tube, an insulated handle connected to said plunger, a needlelike member carried by said plunger, resilient means for normally retaining said plunger and needle-like member within the tube, the end of said needle-like member extensible through the opening in the plate, means within the tube for limiting the movement of the plunger to the tube when pressure is exerted upon the handle, the movement Vof the plunger extending the needle-like member through the opening in the plate, an arm extending downwardly from and pivotally connected. tQ Said tube,

"said tester rotatable in relation to said plate so that the arm is capable of asssuming a vertical position without rotation of the plate and the arm is adjustable to contact portions of the motor block to form a ground.

5. A spark plug tester including, a tube having an aperture in the upper side thereof, a plate rotatably mounted on the end of said tube and having an opening therein, the opening being in alignment with said tube,

a plunger having a recess formed in its upper surface and a wall at one end of said recess, said plunger slidably mounted in said tube, an insulated handle connected to said plunger, a needle-like member carried by said plunger, resilient means for normally retaining said plunger and needle-like member within the tube, one

end of said needle-like member extensible beyond the end of the tube upon the handle being operated to compress the resilient means, a clip having a stop member and extensions, the stop member extending into the aperture formed in the tube and adapted to contact the wall formed at one end of the recess in the surface of the plunger and limit the movement of the plunger, an arm extending from said clip and means for connecting the extensions together and providing pivotal means for the arm, said tester rotatable in relation to said plate so that the arm is capable of assuming a vertical position without rotation of the plate and the arm is adjustable to contact portions of the motor block to form a ground.

6. A spark plug tester adapted to be used in associl ation with an internal combustion engine of the multif1 a needle-like member carried by said plunger, resilient means for normally retaining said plunger and needlelike member within the tube, the end of said needle-like member extensible through the end of the rotatable plate with means for confining the movement of the plunger to the tube when pressure is exerted upon the handle, the movement of the plunger extending the needle-like member through the opening in the plate, said needlelike member adapted to pierce the rubber cap covering the spark plug terminal, the tube rotatable in relation to said plate so that the arm is adjustable to contact portions of the motor block to form a ground without removing the plate from contact with the rubber cap.

7. A spark plug tester adapted to be used in associationy with an internal combustion engine of the multilcylinder type utilizing spark plugs having rubber caps over the spark plug terminals, said tester including a tube, a plunger slidably mounted in said tube, an insulated handle connected to said plunger, a plate mounted on the end of said tube and having an opening therein, said plate adapted to contact the rubber cap covering the terminal, an arm extending downwardly from andpivotally connected to said tube, said arm adapted to contact the engine block to short the current, a needlelike member carried by said plunger, resilient means for normally retaining said plunger and needle-like member within the tube, the end of said needle-like member extensible through the opening in the plate, means for extendingv the needle-like member through the opening in the plate after the `plate is in position against the terminal and the arm' is in contact with the block.

yReferences Cited in the le of this patent UNITED STATES PATENTS 

